1. Field of the Invention
The present invention relates to an electric lamp, in particularly to a novel electrodless globe florescent lamp having high ruminant efficiency.
2. Description of the Related Art
A conventional electrodless globe florescent lamp as shown by FIG. 1 comprises a globe shield 1′, an inner 2′ disposed inside said shield, and a power coupler installed inside said inner 2′. Wherein, said power coupler is consisted of a ferrite power coupling magnetic core 42′, a weaving line 44′, and a radiating stick 46′.
The truth is that, the electrodes readily affect the lighting life of the lamp. Therefore, the elimination of electrodes results in the lamp of an unmatched life, so that the illuminant of the electrodless lamp has the efficiency of a preferable long life, a favorable energy-saving effect, and a higher illuminant performance than those of the conventional lamp. As a result, the electrodless lamp can be extensively adapted to various illuminating occasions.
The electrodless florescent lamp relies on the same ruminant fundamental principles as those of a daylight lamp. The free electrons in the lamp are excited by an electromagnetic field to result in acceleration. Whereby, the kinetic electrons collide with the mercury atoms to excite the mercury atoms if the kinetic energy of the electrons is large enough, so that the kinetic energy of the electrons would be absorbed by the mercury atoms to be converted into an excited state. That is to say, the electrons within the mercury are leveled up from a lower stable level to a higher energy state. However, the electrons of the higher energy state are unstable; that is, the electrons would readily fall back to a ground state. When the excited electrons in the atoms fall back to the ground state, the absorbed energy would be emitted as a radiation photon (253.7 nm UV). In this manner, the UV radiation is converted and cooperated with fluorescent powder coated on the surface of the lamp to visible light.
Moreover, since the electrons do not exist in the electrodless florescent lamp, the power to keep the lamp lighting counts on an electromagnetic coupling, which is specifically directed to a power coupler. An energy source of 50 Hz or 60 Hz power frequency provides the electrodless florescent lamp with electric power; whereby, the energy source would then be converted into a high frequency power of 50 to 1000 KHZ to feed a primary winding of a transformer. Further, the plasmic arc developed by the ionizing discharging of an inert gas and the mercury vapor would become a secondary winding of the transformer. The lamp power coupling between the primary and secondary windings would be completed via the high frequency transformer, so that the transmission of the electric energy within the electrodless florescent lamp can be performed.
In addition, the heat of a magnetic core of the electrodless fluorescent lamp's power coupler is produced by the consumption of the magnetic core working in a high frequency, the plasmic arc's thermal radiating conduction through the gas discharging from the electrodless globe fluorescent lamp, and the inner glass's heating temperature via an inelastic collision between the ion and the glass of the inner. Especially, the plasmic arc's thermal radiating conduction through the gas discharging from the electrodless globe fluorescent lamp and the inner glass's heating temperature via an inelastic collision between the ion and the glass of the inner are two of the main factors to induce the heating temperature of the magnetic core of the power coupling. However, the temperature of a working environment of the magnetic core of the power coupler is higher, which is up to 230□ to 250□, so the competence of the power coupler is more adapted to a magnetic core made of manganese and zinc, which have a less power consumption within the frequent scope of 50 to 1000 KHz. Nevertheless, the curie points of the magnetic core made by the above materials are lower to 220□ to 230□. That is to say, the power coupler is hard to work under the condition of a high temperature over the curies points because an unbuilt state would readily occur.
Wherein, if the distance between the magnetic core of the power coupler and the inner is increased, a thermal resistance between the circular discharging zone of the plasmic arc and the power coupler can be accordingly augmented, so that the working temperature of the magnetic core of the power coupler can be lessened. However, the initial ionized discharging of the electrodless fluorescent lamp mainly depends on the circulation of a discharging mode of E-field (capacitive coupling discharge) converted into a discharging mode of H-field (induction field coupling discharge). Whereby, during the initial discharging of the E-field mode, the energy source thereof is provided by a distributed capacitance between the magnetic core winding of the power coupler and the discharging zone of the lamp gas. That is to say, the efficiency of the discharging of the E-field mode is directly affected by the capacity of the capacitance, but the distributed capacitance between the magnetic core winding of the power coupler and the gas discharging zone within the shield would be accordingly lessened by the enlargement of the distance therebetween. As a result, the lessened distributed capacitance would lead the E-field mold to an unavailable discharging, and the electrodless fluorescent lamp could not be started. Therefore, simply increasing the distance between the magnetic core winding of the power coupler and the gas discharging zone of the inner gas to boost the thermal resistance between the circular discharging zone of the plasmic arc and the power coupler is not an available method.
There is also an increment of a metal heat-conducting bar (made by copper or aluminum or other suitable metals) on the magnetic core of the power coupler to remove the heat on the magnetic core of the power coupler, traditionally, but the competence thereof is however not remarkable. The development of this kind of electrodless globe lamp is contrarily limited, especially to those with large powers.